Apocynaceae is a family of flowering plants with characteristics such as the presence of saps or exudates, absent stipules, and bisexual flowers with a superior ovary (Utteridge & Bramley, 2014). A lesser-known species, Vallaris glabra is an evergreen woody climbers known as bread flowers. Among the local Malays, it is commonly known as Bunga kesidang or kerak nasi. The genus name Vallaris is derived from the Latin word meaning "garland," a circular or spiral arrangement of intertwined flowers or leaves, while the epithet name, glabra means "hairless," which refers to this species' smooth and hairless leaves. Vallaris glabra is native in Sumatra, Java, and the Sunda Islands. This species is introduced to west Peninsular Malaysia and central Thailand (Middleton, 1999).
Vallaris glabra is a large climber that thrives in well-drained soils with full sunlight. The flowers bloom in the morning, producing a fragrant scent similar to pandan leaves mixed with burnt rice. The strong scent is believed to attract pollinators such as butterflies, moths, and bees (National Park Singapore, 2021).
Vallaris glabra is popular among people in the Southeast Asia and has been cultivated in Thailand and other Southeast Asian countries for landscaping as the flowers tolerate heavy sunlight well (National Park Singapore, 2021). These flowers can be left to intertwine on a trellis or pergola to create a small garden. In the past, Malay women tied the flowers on their hair and used them as potpourri (combined with pandan leaves) during wedding ceremony (Burkill, 1966).
Recent studies showed that the leaf extract of V. glabra has a broad spectrum and strong potential for antiproliferative (APF) activity compared to other species in the same family, which means the chemical compound contained in the leaf extract tends to suppress cell growth (Sui et al., 2014). Research done by Kruakaew et al. (2017) showed that the chemical compound contained in the extraction of V. glabra leaves showed an antiproliferative effect against lung carcinoma and human cervical and colorectal cancer cells. Meanwhile, a study conducted by Promsomboon et al. (2014) found that extraction from V. glabra contains linalool, a component that has relaxation and stimulating effects.
